Smart card: plastic card (usually the size of a credit card) embedded with a microchip. Some smart cards contain microelectronic chips, and smart cards need to interact with each other through card readers. Smart card is equipped with CPU, RAM and I/O, which can handle a large amount of data by itself without disturbing the work of the host CPU. Smart cards can also filter error data to reduce the burden on the host CPU. It is suitable for occasions with more ports and faster communication speed. The integrated circuit in the card includes CPU, EEPROM, RAM and COS (Chip Operating System) solidified in ROM. The data in the card is divided into external reading and internal processing.